JP6536630B2 - Negative electrode material for lithium ion secondary battery, method of manufacturing negative electrode material for lithium ion secondary battery, negative electrode material slurry for lithium ion secondary battery, negative electrode for lithium ion secondary battery, and lithium ion secondary battery - Google Patents

Description

  The present invention relates to a negative electrode material for lithium ion secondary batteries, a method of manufacturing a negative electrode material for lithium ion secondary batteries, a negative electrode material slurry for lithium ion secondary batteries, a negative electrode for lithium ion secondary batteries, and a lithium ion secondary battery .

  Lithium ion secondary batteries have higher energy density than other secondary batteries such as nickel cadmium batteries, nickel hydrogen batteries, and lead storage batteries. For this reason, it is used as a power source for portable electronic devices such as notebook computers and mobile phones.

  A recent trend in lithium ion secondary battery development is the expansion of applications to electric vehicles and storage power sources in addition to battery compactification and cost reduction for resource saving. Therefore, there is a demand for higher capacity, higher input / output and cost reduction by densifying the negative electrode. As a material for obtaining a high density negative electrode, a carbon material having high crystallinity such as artificial graphite and spherical natural graphite obtained by spheroidizing natural scaly natural graphite has attracted attention.

  In artificial graphite, as disclosed in Japanese Patent Application Laid-Open No. 10-158005, a graphite particle having a secondary particle structure in which a plurality of flat primary particles are aggregated or bound so that the orientation planes become nonparallel. By using these as a negative electrode active material, the cycle characteristics and the rapid charge / discharge characteristics are improved.

The lithium ion secondary battery can increase the energy density per volume by increasing the negative electrode density as described above. However, when a strong press exceeding 1.7 g / cm ³ is applied to increase the density of the negative electrode, the graphite constituting the negative electrode peels off from the current collector, or the anisotropy of the graphite crystal becomes large, and There are many problems such as deterioration of discharge characteristics.

  Spherical natural graphite has a feature that it has high peel strength and is less likely to be peeled from the current collector even when the electrode is pressed with a strong force. However, since the reaction activity with the electrolytic solution is high and the permeability is low, there is room for improvement in the initial charge-discharge efficiency and the high-speed charge-discharge efficiency.

  In a negative electrode material using artificial graphite having a secondary particle structure, the negative electrode material is applied on a current collector and then pressed at a high pressure for densification. At that time, the primary particles constituting the secondary particles may be oriented parallel to the current collector, and the movement of lithium ions to the positive electrode may be impeded, which may cause a decrease in cycle characteristics. By mixing spherical natural graphite for the purpose of increasing the density of the negative electrode material itself, the press pressure after coating can be reduced. However, there is a problem that lattice defects present on the surface of spherical natural graphite easily react with the electrolyte.

  Spherical natural graphite coated with low crystalline carbon or the like requires a strong pressing pressure to harden it and may not reach the target density. Furthermore, the coating layer may peel off or a defect may occur in the press treatment for adjusting the electrode density, and the defect may lower the charge / discharge characteristics, the cycle characteristics and the safety.

  In view of the above, the present invention is a negative electrode material for lithium ion secondary batteries and a negative electrode material for lithium ion secondary batteries capable of obtaining a lithium ion secondary battery excellent in high load characteristics even if high electrode density treatment is performed. An object of the present invention is to provide a manufacturing method, a negative electrode material slurry for a lithium ion secondary battery, a negative electrode for a lithium ion secondary battery, and a lithium ion secondary battery.

  As a result of intensive investigations, the inventors of the present invention have found that Raman measurement includes composite particles including a plurality of flat graphite particles and spherical graphite particles that are assembled or bonded such that the orientation planes are not parallel. The R value of is 0.03 or more and 0.10 or less, and the pore volume obtained by mercury porosimetry is 0.2 mL / g or more and 1.0 mL / g or less in the range of 0.1 μm or more and 8 μm or less By using the negative electrode material for lithium ion secondary batteries which is the following, it discovers that the said subject is solvable and arrived at this invention.

Specific means for solving the above problems include the following embodiments.
<1> A composite particle including a plurality of flat graphite particles which are assembled or bonded such that the orientation planes are not parallel and a spherical graphite particle, and the R value of Raman measurement is 0.03 or more and 0 .10 or less, for a lithium ion secondary battery having a pore volume of 0.2 mL / g or more and 1.0 mL / g or less in the range of 0.1 μm to 8 μm obtained by mercury porosimetry Negative electrode material.

<2> The specific surface area measured by BET method is less than 1.5 m ² / g or more 6.0 m ² / g negative electrode material for a lithium ion secondary battery according to <1>.

<3> saturated tapping density of 0.8 g / cm ³ or more 1.2 g / cm ³ or less <1> or negative electrode material for a lithium ion secondary battery according to <2>.

In the X-ray diffraction pattern by <4> CuKα ray, the intensity ratio (P ₁ ) between the diffraction peak (P ₁ ) of the (101) plane of the hexagonal structure and the diffraction peak (P ₂ ) of the (101) plane of the rhombohedral structure ₂ / _{P 1)} is 0.35 or less <1> to <3> the negative electrode material for lithium ion secondary battery according to any one of.

The negative electrode material for lithium ion secondary batteries of any one of <1>-<4> whose circularity of the <5> above-mentioned spherical graphite particle is 0.8 or more.

<6> (a) obtaining a mixture containing graphitizable aggregate or graphite, a graphitizable binder, a graphitization catalyst and spherical graphite particles, and (b) calcining the mixture The manufacturing method of the negative electrode material for lithium ion secondary batteries of any one of <1>-<5>.

<7> Between the step (a) and the step (b), at least one selected from the group consisting of (c) forming the mixture and (d) heat treating the mixture 6> The manufacturing method of the negative electrode material for lithium ion secondary batteries as described in 6>.

By the manufacturing method of the negative electrode material for lithium ion secondary batteries as described in any one of <8> <1>-<5>, or the negative electrode material for lithium ion secondary batteries as described in <6> or <7> The negative electrode material slurry for lithium ion secondary batteries containing the manufactured negative electrode material for lithium ion secondary batteries, an organic binder, and a solvent.

Lithium ion having a <9> current collector, and a negative electrode material layer containing the negative electrode material for a lithium ion secondary battery according to any one of <1> to <5> formed on the current collector Negative electrode for secondary battery.

The lithium ion secondary battery which has a <10> positive electrode, electrolyte, and the negative electrode for lithium ion secondary batteries as described in <9>.

  According to the present invention, it is possible to obtain a lithium ion secondary battery capable of obtaining a lithium ion secondary battery excellent in high load characteristics even if the electrode density treatment is performed, and manufacture of a negative electrode material for lithium ion secondary battery A method, a negative electrode material slurry for a lithium ion secondary battery, a negative electrode for a lithium ion secondary battery, and a lithium ion secondary battery can be provided.

It is an example of the scanning electron microscope (SEM) image of the composite particle contained in the negative electrode material for lithium ion secondary batteries of this invention.

  Hereinafter, modes for carrying out the present invention will be described in detail. However, the present invention is not limited to the following embodiments. In the following embodiments, the constituent elements (including the element steps and the like) are not essential unless clearly indicated otherwise in principle, in the case where it is clearly indicated in principle. The same applies to numerical values and ranges thereof, and does not limit the present invention.

  In the present specification, the term "step" is included in the term if the purpose of the step is achieved, even if it can not be clearly distinguished from other steps, not only an independent step. Moreover, the numerical range shown using "-" in this specification shows the range which includes the numerical value described before and after "-" as minimum value and the maximum value, respectively. Further, in the present specification, when there are a plurality of substances corresponding to each component in the composition, the content of each component in the composition is the plurality of substances present in the composition unless otherwise specified. Means the total amount of Furthermore, in the present specification, the particle diameter of each component in the composition is the plurality of particles present in the composition unless a plurality of particles corresponding to each component are present in the composition. Mean the value for a mixture of Further, in the present specification, the term “layer” includes the configuration of a shape formed in part in addition to the configuration of the shape formed on the entire surface when observed as a plan view. The term "stacking" refers to stacking layers, two or more layers may be combined, and two or more layers may be removable.

<Anode material for lithium ion secondary battery>
The negative electrode material for a lithium ion secondary battery of the present invention contains composite particles including a plurality of flat graphite particles which are aggregated or bonded so that the orientation planes are not parallel to each other and a spherical graphite particle, and the Raman measurement is performed. The R value of is 0.03 or more and 0.10 or less, and the pore volume obtained by mercury porosimetry is 0.2 mL / g or more and 1.0 mL / g or less in the range of 0.1 μm or more and 8 μm or less It is below.

  By using the negative electrode material for a lithium ion secondary battery, it is possible to obtain a lithium ion secondary battery which is excellent in high load characteristics even when the high electrode density treatment is performed. In addition, when the negative electrode material for lithium ion secondary batteries of the present invention is used, the negative electrode active material is hardly peeled from the current collector even when the negative electrode for lithium ion secondary batteries is subjected to a high electrode density treatment, and the density is increased Is easy. Furthermore, even at high electrode density, it is possible to obtain a lithium ion secondary battery excellent in capacity, efficiency, liquid absorption, safety, low temperature characteristics, charge / discharge load characteristics, and cycle life.

(Composite particles)
The composite particles are not particularly limited as long as the composite particles include a plurality of flat graphite particles which are aggregated or bonded so that the orientation planes are not parallel to one another and spherical graphite particles. For example, a plurality of flat graphite particles may be assembled or bonded such that the orientation planes are nonparallel, and may be bonded to at least a part of the surface of the spherical graphite particles. More specifically, the flat graphite particles may be bonded to at least a part of the surface of the spherical graphite particles via a carbonaceous material derived from a binder. Whether or not the composite particles are formed can be confirmed, for example, by observation with a scanning electron microscope (SEM).

  FIG. 1: is an example of the SEM image of the composite particle contained in the negative electrode material for lithium ion secondary batteries of this invention. Portions shown by dotted lines in the figure are spherical graphite particles. Composite particles (a portion shown by a solid line in the figure) are formed by spherical graphite particles and a plurality of flat graphite particles which are assembled or bonded such that the orientation planes present around them are nonparallel. There is.

  The negative electrode material for a lithium ion secondary battery is formed by collecting or combining a plurality of flat graphite particles, spherical graphite particles, or the flat graphite particles which do not form composite particles in addition to the composite particles. It may also contain agglomerated graphite particles.

(Average particle size (median diameter))
The average particle diameter (median diameter) of the negative electrode material for the lithium ion secondary battery is not particularly limited. From the viewpoint of the influence on the orientation and the permeability of the electrolytic solution, it may be 10 μm to 30 μm, or 15 μm to 25 μm. The average particle size can be measured by a laser diffraction particle size distribution apparatus, and is a particle size (D50) at which integration from the small diameter side is 50% in the volume-based particle size distribution. The average particle diameter of the negative electrode material for a lithium ion secondary battery is an average value including composite particles and graphite particles not forming the composite particles.
In addition, an average particle diameter can be measured on condition of the following using a laser diffraction particle size distribution measuring apparatus (SALD-3000J, Shimadzu Corporation make).
Absorbance: 0.05 to 0.20
Sonication: 1 to 3 minutes

When the negative electrode material for lithium ion secondary batteries is used as a negative electrode, the method for measuring the average particle diameter is as follows: after embedding a sample electrode or an electrode to be observed in an epoxy resin, mirror polishing is carried out to mirror the cross section of the electrode; And a method of producing an electrode cross section using an ion milling apparatus (E-3500, manufactured by Hitachi High-Technologies Corporation) and observing the cross section with a scanning electron microscope. The average particle size in this case is a median value of 100 particle sizes arbitrarily selected from composite particles and graphite particles not forming composite particles.
The sample electrode may be, for example, a mixture of 98 parts by mass of a negative electrode material for lithium ion secondary batteries, 1 part by mass of styrene butadiene resin as a binder, and 1 part by mass of carboxymethylcellulose as a thickener as a solid content. Water is added so that the viscosity at 25 ° C is 1,500 to 2,500 mPa · s to prepare a dispersion, and the dispersion is made to have a thickness of about 70 μm on copper foil having a thickness of 10 μm (during coating) It can be produced by drying for 1 hour at 120 ° C. after coating.

(Flat-shaped graphite particles)
The composite particles include a plurality of flat graphite particles which are assembled or bonded such that the orientation planes are nonparallel.

  The flat graphite particles have a non-spherical shape having a major axis and a minor axis. For example, graphite particles having a scaly, scaly, or partially massive shape may be mentioned. More specifically, when the length in the major axis direction is A and the length in the minor axis direction is B, the aspect ratio represented by A / B may be 1.2 to 5; It may be three to three. The said aspect ratio expanded a graphite particle with a microscope, selected 100 graphite particles arbitrarily, measured A / B, and took the average value.

  The orientation planes of the flat graphite particles being non-parallel means that planes parallel to the surface of the largest cross-sectional area of two or more flat graphite particles (alignment planes) are not in a mutually parallel positional relationship. Say. Whether or not the orientation planes of the flat graphite particles are not parallel to each other can be confirmed by observation of a photomicrograph. The aggregation or bonding of the orientation planes in a non-parallel state suppresses the increase in the orientation of the particles on the electrode, and achieves the effect of obtaining a high charge / discharge capacity.

  The state in which the flat graphite particles are aggregated or bonded means the state in which two or more flat graphite particles are chemically aggregated or bonded via the carbonaceous material. The carbonaceous material may be, for example, a carbonaceous material obtained by carbonizing a binder such as tar or pitch in a firing process. It may be in a coupled state in terms of mechanical strength. Whether or not the flat graphite particles are aggregated or bonded can be confirmed, for example, by observation with a scanning electron microscope.

The number of aggregated or bonded flat graphite particles may be 3 or more, or 10 or more.
The individual particles of the flat graphite particles may have an average particle diameter D50 of 50 μm or less, or 25 μm or less, from the viewpoint of ease of aggregation or bonding. The average particle diameter D50 may be 1 μm or more. The average particle diameter D50 can be measured by a laser diffraction particle size distribution device, and is a particle diameter at which integration from the small diameter side is 50% in a volume-based particle size distribution.

  The raw material of the flat graphite particles is not particularly limited, and examples thereof include artificial graphite, natural graphite, coke, resin, tar, pitch and the like. Among them, graphite obtained from artificial graphite, natural graphite or coke has high crystallinity and becomes soft particles, so that the electrode tends to be easily densified when it is used as an electrode. In addition, when graphite having a high degree of crystallinity is used, the R value of the negative electrode material for lithium ion secondary batteries decreases, and the charge / discharge initial efficiency tends to be improved.

(Spherical graphite particles)
The composite particles include spherical graphite particles. By including spherical graphite particles having high density, the density of the negative electrode material can be made higher than in the case of including only the flat graphite particles, and the pressure applied in the densification treatment can be reduced. it can. As a result, it is possible to suppress the phenomenon that the flat graphite particles are oriented in a direction parallel to the current collector to prevent the movement of lithium ions.

  Examples of spherical graphite particles and raw materials thereof include spherical artificial graphite and spherical natural graphite. From the viewpoint of obtaining a sufficient saturated tap density as the negative electrode material, the spherical graphite particles may be high density graphite particles. Specifically, it may be spherical natural graphite which has been subjected to particle spheroidizing treatment to be highly tap-densed, or spherical graphite particles sintered at 1500 ° C. or higher. When spherical graphite particles used as a raw material are sintered at 1500 ° C. or higher, highly crystalline spherical graphite particles are formed, and the R value of the negative electrode material for lithium ion secondary batteries can be reduced as described above.

  The average particle diameter of the spherical graphite particles is not particularly limited, and may be 5 μm to 40 μm, 8 μm to 35 μm, or 10 μm to 30 μm. The average particle diameter can be measured by a laser diffraction particle size distribution apparatus, and is a particle diameter at which integration from the small diameter side is 50% in a volume-based particle size distribution.

(Roundness of spherical graphite particles)
The roundness of the spherical graphite particles may be 0.80 or more, and may be 0.85 or more. Some of the spherical graphite particles are deformed by mechanical force in the process of manufacturing the negative electrode material for a lithium ion secondary battery. However, the higher the degree of circularity of the spherical graphite particles contained in the negative electrode material for lithium ion secondary batteries, the lower the orientation as the negative electrode material and the better the characteristics as an electrode. As a method for increasing the circularity of the spherical graphite particles contained in the negative electrode material for lithium ion secondary batteries, it is possible to use spherical graphite particles having high circularity as a raw material. The degree of circularity is measured for the portion of spherical graphite particles contained in the composite particles.

The degree of circularity of the spherical graphite particles can be determined by photographing the cross section of the spherical graphite particles according to the following equation.
Circularity = (perimeter of equivalent circle) / (perimeter of cross-sectional image of spherical graphite particle)
Here, "equivalent circle" is a circle having the same area as the cross-sectional image of the spherical graphite particles. The peripheral length of the cross-sectional image of the spherical graphite particles is the length of the outline of the cross-sectional image of the spherical graphite particles taken. In the present invention, the circularity of the present invention enlarges the cross section of the spherical graphite particles by a magnification of 1000 with a scanning electron microscope, and arbitrarily selects 10 spherical graphite particles, and the above method It is the value which measured the degree of circularity and took the average.

  When the negative electrode material for a lithium ion secondary battery is used as a negative electrode, as a method of measuring the degree of circularity of spherical graphite particles, a sample electrode or an electrode to be observed is embedded in an epoxy resin and then mirror polished The method of observing with a scanning electron microscope, the method of producing an electrode cross section using an ion milling apparatus (E-3500, manufactured by Hitachi High-Technologies Corporation) and observing it with a scanning electron microscope, etc. may be mentioned.

  The sample electrode can be produced, for example, in the same manner as the sample electrode used for the measurement of the above-mentioned average particle diameter.

(R value of Raman measurement)
The negative electrode material for a lithium ion secondary battery has an R value of 0.03 or more and 0.10 or less in Raman measurement. The R value may be 0.04 or more and 0.10 or less, or may be 0.05 or more and 0.10 or less. When the R value exceeds 0.10, gas expansion of the lithium ion secondary battery may occur due to an increase in the amount of decomposition reaction of the electrolytic solution, or the initial efficiency may decrease. As a result, application to a high density counter electrode may be substantially difficult. If the R value is less than 0.03, there may be too few graphite lattice defects for insertion and desorption of lithium ions, and the load characteristics of charge and discharge may be degraded.

The R value in Raman spectrum obtained in Raman measurements to be described later, define the intensity IA of a maximum peak in the vicinity of 1580 cm ^-1, the intensity ratio of the intensity IB of a maximum peak around 1360 cm ^-1 and (IB / IA) .

For Raman measurement, a negative electrode material for a lithium ion secondary battery or a negative electrode material for a lithium ion secondary battery is collected using a Raman spectrometer “Laser Raman spectrophotometer (model number: NRS-1000, manufactured by JASCO Corporation)” The sample plate set to flatten the electrode obtained by applying and pressing is irradiated with argon laser light and measurement is performed under the following conditions.
Wavelength of argon laser light: 532 nm
Wavenumber resolution: 2.56 cm ^-1
Measurement range: 1180 cm ^{-1 to} 1730 cm ^-1
Peak research: background removal

  As a method for obtaining a negative electrode material for a lithium ion secondary battery having an R value of Raman measurement of 0.03 or more and 0.10 or less, a method of firing spherical graphite particles as described above can be mentioned. Furthermore, setting the ratio of the residual carbon component derived from binder components, such as pitch, used as a raw material to 30 mass% or less of the whole negative electrode material for lithium ion secondary batteries is mentioned. The low crystallinity component such as the binder component is necessary to form the composite particles by aggregating or bonding the above-described flat graphite particles, but the crystallinity development by graphitization is slow and the residual carbon ratio is also Low. This causes a decrease in productivity, and the particles after graphitization tend to be hard. As a result, load may be applied to the surface of the graphite particles when performing pulverization for density adjustment and density adjustment pressing when forming an electrode, lattice defects may be generated, and the R value may increase. Therefore, it is effective to limit the addition amount so that the residual carbon content of the binder component is 30% by mass or less of the whole negative electrode material for lithium ion secondary batteries.

(Pore volume)
The negative electrode material for a lithium ion secondary battery has a pore diameter of 0.2 mL / g or more and 1.0 mL / g or less in a pore diameter range of 0.1 μm to 8 μm obtained by mercury porosimetry. If the pore volume is less than 0.2 mL / g, the amount of electrolyte serving as a lithium ion transfer medium in a lithium ion secondary battery is too small, and the high-speed charge / discharge characteristics tend to be degraded. When the pore volume exceeds 1.0 mL / gm, the oil absorption capacity of additives such as organic adhesives and thickeners is increased, and the productivity is lowered due to abnormal paste viscosity, lack of current collector adhesion, etc. It tends to occur.

  The pore volume of 0.1 μm or more and 8 μm or less obtained by the mercury intrusion method may be 0.4 mL / g or more and 0.8 mL / g or less, and may be 0.5 mL / g or more and 0.7 mL / g or less It may be. The pore volume of the negative electrode material for lithium ion secondary batteries can be made into the above-mentioned range, for example, by appropriately adjusting the compounding ratio of the spherical graphite particles.

The pore volume is obtained by the mercury porosimetry shown below.
The mercury intrusion method uses “Pore distribution measuring apparatus Autopore 9520 type, manufactured by Shimadzu Corporation”. The mercury parameters are set to a mercury contact angle of 130.0 ° and a mercury surface tension of 485.0 mN / m (485.0 dynes / cm). A sample (about 0.3 g) is taken in a standard cell and measured under conditions of an initial pressure of 9 kPa (about 1.3 psia, equivalent to a pore diameter of about 140 μm). The volume of the pore volume in the range of 0.1 μm to 8 μm is calculated from the obtained pore distribution.

(Specific surface area)
The negative electrode material for a lithium ion secondary battery may have a specific surface area measured by a BET method of 1.5 m ² / g or more and 6.0 m ² / g or less, and 2.5 m ² / g or more. It may be 0 m ² / g or less.
The said specific surface area is a parameter | index which shows the area of an interface with electrolyte solution. That is, when the value of the specific surface area is 6.0 m ² / g or less, the area of the interface between the negative electrode material for lithium ion secondary battery and the electrolytic solution is not too large, and the reaction field of the decomposition reaction of the electrolytic solution is increased. May be suppressed to suppress gas generation, and the initial charge / discharge efficiency may be good. In addition, when the value of the specific surface area is 1.5 m ² / g or more, the current density per unit area does not increase rapidly, and the load is suppressed. Therefore, charge / discharge efficiency, charge acceptance, rapid charge / discharge characteristics, etc. Tend to be good.

  The measurement of the specific surface area can be performed by a known method such as BET method (nitrogen gas adsorption method). Preferably, an electrode obtained by applying and pressurizing a negative electrode material for lithium ion secondary batteries or a negative electrode material for lithium ion secondary batteries to a measurement cell is filled with a measurement cell, and heated before heating at 200 ° C. while vacuum degassing. Nitrogen gas is adsorbed to the sample obtained by the treatment using a gas adsorption apparatus (ASAP 2010, manufactured by Shimadzu Corporation). The obtained sample is subjected to BET analysis by the 5-point method to calculate the specific surface area. The specific surface area of the negative electrode material for lithium ion secondary batteries may be adjusted, for example, by adjusting the average particle size (if the average particle size is decreased, the specific surface area tends to increase, and if the average particle size is increased, the specific surface area is decreased. To the above range).

(Saturated tap density)
The negative electrode material for a lithium ion secondary battery may have a saturation tap density of 0.8 g / cm ³ or more and 1.2 g / cm ³ or less, and 0.9 g / cm ³ or more and 1.1 g / cm ³ or less It may be.

The saturation tap density is an indicator of electrode densification. The electrode obtained by apply | coating the negative electrode material for lithium ion secondary batteries on a collector as the said saturation tap density is 1.2 g / cm < ³ > or less becomes high density, and it is added for electrode density adjustment. The pressure can be reduced, and the graphite particles in the electrode can easily maintain its original shape. If the graphite particles can maintain their original shape, the orientation of the electrode plate is small, lithium ions can easily enter and leave, and the cycle characteristics can be improved. If the saturation tap density is too high, the pore volume may be reduced, and the amount of the electrolyte serving as a lithium ion transfer medium in the battery may be reduced to deteriorate the high-speed charge / discharge characteristics. Therefore, it is preferable to adjust the saturation tap density so that the pore volume is not too low. By adjusting the proportion of spherical graphite particles appropriately (by increasing the proportion of spherical graphite particles, the tap density tends to increase and when the proportion decreases, the tap density tends to decrease). It can be in the above range.

  The measurement of the saturated tap density can be performed by a known method. Preferably, 100 ml of a negative electrode material for a lithium ion secondary battery is placed in a measuring cylinder using a filling density measuring device (KRS-406, manufactured by Kuramochi Scientific Instruments Mfg. Co., Ltd.), and tap until the density is saturated (from a predetermined height Calculate by dropping the measuring cylinder).

(Rhohedral structural peak intensity ratio)
The negative electrode material for a lithium ion secondary battery has a diffraction peak (P ₁ ) of a (101) plane of a hexagonal crystal structure and a diffraction peak (P1) of a (101) plane of a rhombohedral structure in an X-ray diffraction pattern by CuKα rays. ₂₎ the intensity ratio _(P 2 / _{P 1)} is may be 0.35 or less, and may be 0.30 or less. When the peak intensity ratio (P ₂ / P ₁ ) is 0.35 or less, the degree of graphitization of the negative electrode material for a lithium ion secondary battery is higher, and the charge / discharge capacity tends to be high.

The said rhombohedral structure peak intensity ratio is a diffraction line (P1: diffraction angle 43.2 degrees) of the rhombohedral structure and a diffraction line (P2: diffraction angle 44.3) of the hexagonal crystal structure in the X-ray diffraction pattern using CuK alpha rays. Can be calculated from the intensity ratio of Here, the diffraction angle is expressed by 2θ (θ is a Bragg angle), but the diffraction line of the (101) plane of the rhombohedral structure appears at the diffraction angle 43.2 degrees, and the diffraction angle is 6 A diffraction line of (101) plane of crystal structure appears.
The rhombohedral structure peak intensity ratio can be in the above range by adjusting the degree of graphitization (for example, adjusting the heat treatment temperature).

<Method of manufacturing negative electrode material for lithium ion secondary battery>
The method for producing a negative electrode material for a lithium ion secondary battery comprises: (a) obtaining a mixture comprising graphitizable aggregate or graphite, a graphitizable binder, a graphitization catalyst and spherical graphite particles (b B.) Firing the mixture.

  According to the above-mentioned method, the composite particle includes a plurality of flat graphite particles which are assembled or bonded such that the orientation planes are not parallel and the spherical graphite particles, and the R value of the Raman measurement is 0. Lithium ion 2 having a pore volume of 0.2 mL / g or more and 1.0 mL / g or less which is 03 or more and 0.1 or less, and a pore diameter obtained by mercury porosimetry is in a range of 0.1 μm or more and 8 μm or less A negative electrode material for a secondary battery can be manufactured.

  Further, according to the above method, when the raw material is graphitized by firing, heavy metals, magnetic foreign substances and impurities contained in the raw material are removed by high heat, so acid treatment, washing with water and the like of spherical graphite particles such as natural graphite are performed. There is no need. Thereby, the manufacturing cost can be reduced, and a highly safe negative electrode material for a lithium ion secondary battery can be provided. Furthermore, by using spherical graphite particles which are already graphite in addition to the graphitizable aggregate as at least a part of the raw material, the amount of the graphitization catalyst required for the graphitization of the raw material is reduced, and the firing time for graphitization is Can reduce manufacturing costs. As a result, it is possible to provide a more inexpensive negative electrode material for a lithium ion secondary battery while using expensive artificial graphite. Moreover, the binder component used for preparation of the negative electrode material for lithium ion secondary batteries can be reduced.

  In the above method, spherical graphite particles are also fired together with other raw materials. This makes it possible to lower the R value of Raman measurement of the negative electrode material for a lithium ion secondary battery, as compared to the case where spherical graphite particles are mixed with a material obtained by firing and graphitizing other raw materials.

In step (a), the graphitizable aggregate or graphite, the graphitizable binder, the graphitization catalyst and the spherical graphite particles are mixed to obtain a mixture.
Examples of the graphitizable aggregate include coke such as fluid coke, needle coke, mosaic coke and the like. In addition, aggregates that are already graphite such as natural graphite and artificial graphite may be used. The graphitizable aggregate is not particularly limited as long as it is powdery. Among them, coke powder which is easily graphitized such as needle coke may be used. The graphite is not particularly limited as long as it is a powder. The particle size of the graphitizable aggregate or graphite is preferably smaller than the particle size of the flat graphite particles.
Examples of the spherical graphite particles include spherical artificial graphite and spherical natural graphite.
Examples of the graphitizable binder include coal-based, petroleum-based, artificially-formed pitches and tars, thermoplastic resins, thermosetting resins and the like.
Examples of the graphitization catalyst include substances having graphitization catalysis such as silicon, iron, nickel, titanium, and boron, and carbides, oxides, and nitrides of these substances.

  The content of the spherical graphite particles may be 5% by mass to 80% by mass, or 8% by mass to 75% by mass with respect to 100 parts by mass of the graphitizable aggregate or graphite. 8 mass%-70 mass% may be sufficient. When the content of the spherical graphite particles is in the above range, high density and high charge / discharge capacity tend to be obtained.

  The content of the graphitizable binder may be 5% by mass to 80% by mass, or 10% by mass to 80% by mass with respect to 100 parts by mass of the graphitizable aggregate or graphite. 15 mass%-80 mass% may be sufficient. By setting the addition amount of the graphitizable binder to an appropriate amount, it is possible to suppress that the aspect ratio and the specific surface area of the flat graphite particles to be produced become too large. Furthermore, the amount of the graphitizable binder is suppressed so that the residual carbon content derived from the binder after firing is 30% by mass or less of the entire negative electrode material for lithium ion secondary batteries, thereby achieving R in Raman measurement. It can be suppressed that the value becomes too large.

  The graphitization catalyst may be added in an amount of 1 part by mass to 50 parts by mass with respect to 100 parts by mass in total of the graphitizable aggregate or graphite and the graphitizable binder. When the amount of the graphitization catalyst is 1 part by mass or more, the development of crystals of the graphitic particles is good, and the charge / discharge capacity tends to be good. On the other hand, when the amount of the graphitization catalyst is 50 parts by mass or less, mixing of the graphitizable aggregate or graphite, the graphitizable binder, the graphitization catalyst and the spherical graphite particles can be performed more uniformly. Workability tends to be good. There is no particular limitation on the method of mixing the graphitization catalyst, and any mixing method may be used as long as the graphitization catalyst is present inside or on the surface of the particles in the mixture at least before calcination for graphitization.

  There are no particular limitations on the method of mixing the graphitizable aggregate or graphite, the graphitizable binder, the graphitization catalyst, and the spherical graphite particles. For example, a kneader or the like can be used. The mixing may be performed at a temperature above the softening point of the binder. Specifically, if the graphitizable binder is pitch, tar or the like, it may be 50 ° C to 300 ° C, and if it is a thermosetting resin, it may be 20 ° C to 100 ° C. Good.

  In the step (b), the mixture obtained in the step (a) is fired. Thereby, the graphitizable component in the mixture is graphitized. The firing is preferably performed in an atmosphere in which the mixture is difficult to oxidize, and examples thereof include a method of firing in a nitrogen atmosphere, argon gas, or vacuum. The firing temperature is not particularly limited as long as it is a temperature at which the graphitizable component can be graphitized. For example, the temperature may be 1500 ° C. or higher, 2000 ° C. or higher, 2500 ° C. or higher, or 2800 ° C. or higher. The firing temperature may be 3200 ° C. or less. When the firing temperature is 1500 ° C. or more, change in crystals occurs. When the calcination temperature is 2000 ° C. or more, the development of graphite crystals becomes favorable, and the amount of the graphitization catalyst remaining in the produced graphitic particles tends to decrease (an increase in the amount of ash is suppressed). In any case, the charge / discharge capacity and the cycle characteristics of the battery tend to be good. On the other hand, it can suppress that a part of graphite sublimes that a calcination temperature is 3200 degrees C or less.

  In the method of manufacturing the negative electrode material for a lithium ion secondary battery, from the step of (c) molding the mixture and the step of (d) heat-treating the mixture between the step (a) and the step (b) And at least one selected from the group consisting of Specifically, even if only the step (b) is performed after the step (a), or whether only the step (c) is performed after the step (a), the step (b) and the step (b) after the step (a) Even if c) is carried out in this order, the step (c) and the step (b) may be carried out in this order after the step (a).

  The molding in the step (c) of molding the mixture can be performed, for example, by crushing the mixture and placing it in a container such as a mold.

  Heat treating the mixture in the step (d) of heat treating the mixture is preferable from the viewpoint of promoting graphitization. When performing the said heat processing, it is more preferable to carry out after shape | molding the said mixture in process (c). The heat treatment may be performed at 1500 ° C. or higher, and may be performed at 2500 ° C. or higher.

  If the mixture is not shaped and pulverized to adjust the particle size before firing, the graphitized product obtained after firing may be pulverized to obtain a desired average particle size. Alternatively, the mixture may be shaped and crushed to adjust the particle size before firing, and the resulting graphitized may be further crushed after firing. There is no particular limitation on the method of grinding the graphitized material. For example, it can be carried out by a known method using a jet mill, a vibration mill, a pin mill, a hammer mill or the like. The average particle diameter (median diameter) after grinding may be 100 μm or less, and may be 10 μm to 50 μm.

  The graphitized material after firing and crushing may be subjected to isotropic pressure treatment. As a method of the isotropic pressure treatment, for example, a method of filling a container made of rubber or the like after firing and crushing into a container made of rubber or the like, sealing the container, and subjecting the container to isotropic pressure treatment with a press It can be mentioned. It is preferable that the isotropic pressure-treated graphitized material be crushed by a cutter mill or the like and sized by a sieve or the like.

  The method mentioned above is an example of the manufacturing method of the negative electrode material for lithium ion secondary batteries. You may manufacture the negative electrode material for lithium ion secondary batteries by methods other than the above. As a method other than the above, after preparing a graphite particle (aggregated graphite particle) formed by aggregating or bonding a plurality of flat graphite particles such that the orientation plane is not parallel, the spherical graphite particles are mixed Methods of forming composite particles can be mentioned. With respect to the method for producing massive graphite particles, the description of Japanese Patent No. 3285520, Japanese Patent No. 3325021, etc. can be referred to.

(Anode active material for lithium ion secondary battery)
The negative electrode active material for a lithium ion secondary battery of the present invention contains carbonaceous particles or storage metal particles having at least one of the shape or the physical properties different from that of the graphite particles contained in the negative electrode for a lithium ion secondary battery. The negative electrode active material for a lithium ion secondary battery is preferably any one selected from the group consisting of natural graphite, artificial graphite, amorphous coated graphite, resin coated graphite, amorphous carbon, and storage metal particles. It further contains the above lithium ion storage structure.

(Slurry for negative electrode material for lithium ion secondary battery)
The negative electrode material slurry for a lithium ion secondary battery of the present invention is a negative electrode material for a lithium ion secondary battery, or a negative electrode material for a lithium ion secondary battery produced by the method for producing a negative electrode material for a lithium ion secondary battery And an organic binder and a solvent.

  There is no particular limitation on the organic binder. For example, styrene-butadiene rubber, ethylenic unsaturated carboxylic acid ester (methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, (meth) acrylonitrile, hydroxyethyl (meth) acrylate etc.), and ethylenic (Meth) acrylic copolymers derived from unsaturated carboxylic acids (acrylic acid, methacrylic acid, itaconic acid, fumaric acid, maleic acid etc.), polyvinylidene fluoride, polyethylene oxide, polyepichlorohydrin, polyphosphazene, poly Polymer compounds such as acrylonitrile, polyimide, polyamide imide and the like can be mentioned.

  The solvent is not particularly limited. For example, organic solvents such as N-methylpyrrolidone, dimethylacetamide, dimethylformamide, γ-butyrolactone and the like are used.

  The said negative electrode material slurry for lithium ion secondary batteries may also contain the thickener for adjusting a viscosity as needed. Examples of the thickener include carboxymethylcellulose, methylcellulose, hydroxymethylcellulose, ethylcellulose, polyvinyl alcohol, polyacrylic acid and salts thereof, oxidized starch, phosphorylated starch, casein and the like.

  The said negative electrode material slurry for lithium ion secondary batteries may mix a conductive support agent as needed. Examples of the conductive aid include carbon black, graphite, acetylene black, oxides exhibiting conductivity, nitrides exhibiting conductivity, and the like.

(Anode for lithium ion secondary battery)
The negative electrode for a lithium ion secondary battery of the present invention has a current collector, and a negative electrode material layer containing the negative electrode material for a lithium ion secondary battery formed on the current collector.

  The material and shape of the current collector are not particularly limited. For example, materials such as strip-shaped foil, strip-shaped piercing foil, and strip-shaped mesh made of metal or alloy such as aluminum, copper, nickel, titanium and stainless steel can be used. In addition, porous materials such as porous metal (foam metal) and carbon paper can also be used.

  The method of forming the negative electrode material layer containing the negative electrode material for lithium ion secondary batteries on a collector is not specifically limited. For example, it can carry out by well-known methods, such as a metal mask printing method, an electrostatic coating method, a dip coating method, a spray coating method, a roll coating method, a doctor blade method, a gravure coating method, a screen printing method. When integrating the said negative electrode material layer and a collector, it can carry out by well-known methods, such as a roll, a press, and these combination.

  The negative electrode for a lithium ion secondary battery obtained by forming the negative electrode layer on the current collector may be heat-treated according to the type of the organic binder used. By heat treatment, the solvent is removed, the hardening of the binder progresses, and the adhesion between particles and between the particles and the current collector can be improved. The heat treatment may be performed in an inert atmosphere such as helium, argon or nitrogen or in a vacuum atmosphere to prevent oxidation of the current collector during processing.

The negative electrode for a lithium ion secondary battery may be pressed (pressure treatment) before the heat treatment is performed. The electrode density can be adjusted by pressure treatment. The electrode density may be ^{1.5g / cm 3 ~1.9g / cm 3} , may be ^{1.6g / cm 3 ~1.8g / cm 3} . As the electrode density is higher, the volumetric capacity is improved, the adhesion of the negative electrode layer to the current collector is improved, and the cycle characteristics are also improved.

(Lithium ion secondary battery)
The lithium ion secondary battery of the present invention has a positive electrode, an electrolyte, and the above-described negative electrode for a lithium ion secondary battery. The lithium ion secondary battery may be, for example, configured to be disposed such that the negative electrode and the positive electrode face each other via a separator, and to which an electrolytic solution containing an electrolyte is injected.

  The positive electrode can be obtained by forming a positive electrode layer on the surface of the current collector in the same manner as the negative electrode. As the current collector, materials such as a strip-shaped foil made of metal or alloy such as aluminum, titanium and stainless steel, a strip-shaped piercing foil, and a strip-shaped mesh can be used.

The positive electrode material used for the positive electrode layer is not particularly limited. For example, metal compounds capable of doping or intercalating lithium ions, metal oxides, metal sulfides, and conductive polymer materials can be mentioned. Furthermore, lithium cobaltate (LiCoO ₂ ), lithium nickelate (LiNiO ₂ ), lithium manganate (LiMnO ₂ ), and their complex oxides (LiCo _x Ni _y Mn _z O ₂ , x + y + z = 1, 0 <x , 0 <y; LiNi _2-x Mn _x O ₄ , 0 <x ≦ 2), lithium manganese spinel (LiMn ₂ O ₄ ), lithium vanadium compound, V ₂ O ₅ , V ₆ O ₁₃ , VO ₂ , MnO ₂ , TiO ₂ , MoV ₂ O ₈ , TiS ₂ , V ₂ S ₅ , VS ₂ , MoS ₂ , MoS ₃ , Cr ₃ O ₈ , Cr ₂ O ₅ , olivine type LiMPO ₄ (M: Co, Ni, Mn, Fe ), Conductive polymers such as polyacetylene, polyaniline, polypyrrole, polythiophene, polyacene etc., porous carbon etc. alone or in combination of two or more Can be used in combination. Among them, lithium nickelate (LiNiO ₂ ) and its complex oxide (LiCo _x Ni _y Mn _z O ₂ , x + y + z = 1, 0 <x, 0 <y; LiNi _2-x Mn _x O ₄ , 0 <x ≦ 2 ) Is suitable as a positive electrode material because of its high capacity.

  Examples of the separator include nonwoven fabrics mainly composed of polyolefins such as polyethylene and polypropylene, cloths, microporous films, and combinations thereof. When the lithium ion secondary battery has a structure in which the positive electrode and the negative electrode are not in contact with each other, it is not necessary to use a separator.

Examples of the electrolyte include lithium salts such as LiClO ₄ , LiPF ₆ , LiAsF ₆ , LiBF ₄ , LiSO ₃ CF ₃ , ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, fluoroethylene carbonate, cyclopentanone, sulfolane, 3-Methylsulfolane, 2,4-dimethylsulfolane, 3-methyl-1,3-oxazolidin-2-one, γ-butyrolactone, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, butyl methyl carbonate, ethyl propyl Carbonate, butylethyl carbonate, dipropyl carbonate, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-di It is possible to use a so-called organic electrolytic solution which is dissolved in a non-aqueous solvent such as oxolane, methyl acetate and ethyl acetate alone or in a mixture of two or more components. Among them, an electrolytic solution containing fluoroethylene carbonate tends to form a stable SEI (solid electrolyte interface) on the surface of the negative electrode material, and is suitable because the cycle characteristics are significantly improved.

  The form of the lithium ion secondary battery of the present invention is not particularly limited, and examples thereof include a paper type battery, a button type battery, a coin type battery, a laminated type battery, a cylindrical type battery, and a square type battery. The negative electrode material for a lithium ion secondary battery can be applied to general electrochemical devices such as a hybrid capacitor having charge and discharge mechanism in which lithium ions are inserted and released in addition to the lithium ion secondary battery. .

  Hereinafter, the present invention will be more specifically described by way of synthesis examples, examples and comparative examples, but the present invention is not limited to the following examples.

Example 1
(1) 50 parts by mass of coke powder having an average particle size of 10 μm, 20 parts by mass of tar pitch, 20 parts by mass of silicon carbide, and 10 parts by mass of spherical natural graphite (circularity 0.92) having an average particle size of 20 μm The mixture was stirred at 100 ° C. for 1 hour to obtain a mixture. Next, this mixture was ground to 25 μm, and the obtained ground powder was placed in a mold and formed into a rectangular solid. The obtained rectangular solid was heat-treated at 1000 ° C. in a nitrogen atmosphere, and then fired at 2800 ° C. to graphitize a graphitizable component. The obtained graphite compact was pulverized to obtain a graphite powder (negative electrode material for lithium ion secondary battery).
The average particle size, R value, pore volume, specific surface area, saturated tap density, and rhombohedral structure peak intensity ratio of the graphite powder obtained above were measured. The results are shown in Table 1. Each measurement was performed by the method described above.

(2) 98 parts by mass of the graphite powder obtained above, 1 part by mass of styrene butadiene rubber (BM-400B, manufactured by Nippon Zeon Co., Ltd.), and 1 part by mass of carboxymethylcellulose (CMC 2200, manufactured by Daicel Co., Ltd.) A slurry was made. This slurry is applied to a current collector (copper foil with a thickness of 10 μm), dried in air at 110 ° C. for 1 hour, and the applied material (active material) has an electrode density of 1.80 g / cm ³ with a roll press. It integrated on conditions, and produced the negative electrode for lithium ion secondary batteries.

  The orientation and peel strength of the negative electrode for a lithium ion secondary battery were each measured by the methods shown below. The measurement results are shown in Table 1.

<Alignability>
It calculated | required by measuring the surface of a sample electrode with the X-ray-diffraction apparatus which uses a CuK alpha ray as X-ray source. Specifically, the X-ray diffraction pattern of the surface of the sample electrode is measured, and a carbon (002) surface diffraction peak detected near the diffraction angle 2θ = 26 to 27 degrees and around the diffraction angle 2θ = 70 to 80 degrees It calculated | required by following formula (1) from the intensity | strength with the carbon (110) surface diffraction peak detected.
(002) surface diffraction peak intensity / (110) surface diffraction peak intensity ..... Formula (1)

<Peeling strength>
By using an autograph (manufactured by Shimadzu Corporation), a pressure-sensitive adhesive tape was attached to the surface of the active material, and the peel strength was measured at the interface between the current collector (copper foil) and the active material by pulling perpendicularly to the electrode surface.

(3) A mixture of ethylene carbonate / ethyl methyl carbonate (3/7 volume ratio) and vinylene carbonate (0.5 mass%) containing metal lithium as the positive electrode and positive electrode and 1.0 M LiPF ₆ as the electrolytic solution (3) A 2016 type coin cell was manufactured using the liquid, a polyethylene microporous film with a thickness of 25 μm as a separator, and a copper plate with a thickness of 230 μm as a spacer.
The charge capacity, discharge capacity, efficiency, rapid discharge maintenance rate, and low temperature charge maintenance rate of the lithium ion secondary battery were measured by the methods described below. The measurement results are shown in Table 1.

<Charge capacity and discharge capacity>
The measurement of charge and discharge capacity (initial charge and discharge capacity) is sample weight: 15.4 mg, electrode area: 1.54 cm ² , measurement temperature: 25 ° C., electrode density: 1700 kg / m ³ , charge condition: constant current charge 0. The test was performed under the conditions of 434 mA, constant voltage charge 0 V (Li / Li ⁺ ), cut current 0.043 mA, discharge condition: constant current discharge 0.434 mA, cut voltage 1.5 V (Li / Li ⁺ ).
The measurement of the discharge capacity was performed according to the above-mentioned charge condition and discharge condition.

<Efficiency>
The efficiency was the ratio (%) of the value of the discharge capacity to the value of the charge capacity measured.

<Rapid discharge maintenance rate>
Using the coin cell produced above, the rapid discharge maintenance rate was measured in the following procedure (1) to (5) in a thermostat at 25 ° C.
(1) Charged to 0 V (V vs. Li ^/ Li ⁺ ) at a constant current of 0.434 mA, then charged to a current of 0.043 mA at a constant voltage of 0 V, rested for 30 minutes, and measured the charge capacity .
(2) A discharge was performed to 1.5 V (V vs. Li ^/ Li ⁺ ) at a constant current of 0.434 mA, and a 30-minute rest cycle test was performed to measure the discharge capacity.
(3) In the second cycle, the charge and discharge of (1) and (2) were repeated to measure the charge capacity and the discharge capacity.
(4) After the third cycle, the charge condition is the same as (1), and the discharge condition is the constant current value of (2) 4.34 mA (third cycle), 6.51 mA (fourth cycle), 8 It measured by .68 mA (5th cycle), 10.85 mA (6th cycle), and 13.02 mA (2.4C) (7th cycle).
(5) The measurement of the rapid discharge maintenance rate was obtained by dividing each discharge capacity by the discharge capacity of the second cycle and calculating the maintenance rate (%) for the discharge capacities measured in 3 to 7 cycles.

<Low temperature charge maintenance rate>
Using the coin cell produced above, the low-temperature charge retention rate was measured by the following procedures (6) to (8).
(6) In the thermostat at 25 ° C., charge and discharge were performed according to the procedure of (1) (2) (3) above, and the charge capacity was measured.
(7) After the termination of discharge in (6), after the temperature in the thermostatic chamber became 0 ° C., the charge capacity was measured by maintaining the temperature at 0 ° C. and charging in the above (1).
(8) The measurement of the low-temperature charge retention rate is the charge capacity when reaching 0 V (V vs. Li ^/ Li ⁺ ) at a constant current of 0.434 mA at 0 ° C. of (6) at 25 ° C. of (3) The maintenance rate (%) was calculated by dividing by the charge capacity when reaching 0 V (V vs. Li ^/ Li ⁺ ) at a constant current of 0.434 mA.

Example 2
The graphite powder obtained in Example 1 is filled in a rubber container and sealed, and then the isostatic pressing is performed on the rubber container with a pressure machine at a pressure of 9800 N / cm ² (1000 kgf / cm ² ). went. Then, the graphite powder was crushed by a cutter mill and granulated by a sieve to obtain a graphite powder of Example 2.
A negative electrode for a lithium ion secondary battery and a lithium ion secondary battery were produced in the same manner as in Example 1, and measurements were conducted in the same manner as in Example 1. The results are shown in Table 1.

[Example 3]
Graphite powder of Example 3 was prepared in the same manner as Example 2, except that coke powder, tar pitch and silicon carbide were mixed, stirred and pulverized to obtain pulverized powder, and then spherical natural graphite was mixed with the pulverized powder. Obtained.
A negative electrode for a lithium ion secondary battery and a lithium ion secondary battery were produced in the same manner as in Example 1, and measurements were conducted in the same manner as in Example 1. The results are shown in Table 1.

Example 4
Graphite powder of Example 4 was prepared in the same manner as Example 2, except that coke powder, tar pitch and spherical natural graphite were mixed, stirred and pulverized to obtain pulverized powder, and then silicon carbide was mixed with the pulverized powder. Obtained.
A negative electrode for a lithium ion secondary battery and a lithium ion secondary battery were produced in the same manner as in Example 1, and measurements were conducted in the same manner as in Example 1. The results are shown in Table 1.

[Example 5]
Graphite powder of Example 5 was prepared in the same manner as Example 2, except that coke powder and tar pitch were mixed, stirred and pulverized to obtain pulverized powder, and then silicon carbide and spherical natural graphite were mixed with the pulverized powder. Obtained.
A negative electrode for a lithium ion secondary battery and a lithium ion secondary battery were produced in the same manner as in Example 1, and measurements were conducted in the same manner as in Example 1. The results are shown in Table 1.

[Example 6]
Example like Example 2 except having changed quantity of coke powder, tar pitch, silicon carbide, and spherical natural graphite into 43 mass parts, 18.5 mass parts, 18.5 mass parts, and 20 mass parts, respectively. Six graphite powders were obtained.
A negative electrode for a lithium ion secondary battery and a lithium ion secondary battery were produced in the same manner as in Example 1, and measurements were conducted in the same manner as in Example 1. The results are shown in Table 1.

[Example 7]
The graphite powder of Example 7 was prepared in the same manner as Example 6, except that coke powder, tar pitch and silicon carbide were mixed, stirred and pulverized to obtain pulverized powder, and then spherical natural graphite was mixed with the pulverized powder. Obtained.
A negative electrode for a lithium ion secondary battery and a lithium ion secondary battery were produced in the same manner as in Example 1, and measurements were conducted in the same manner as in Example 1. The results are shown in Table 1.

[Example 8]
The graphite powder of Example 8 was prepared in the same manner as Example 6, except that coke powder, tar pitch and spherical natural graphite were mixed, stirred and pulverized to obtain pulverized powder, and then silicon carbide was mixed with the pulverized powder. Obtained.
A negative electrode for a lithium ion secondary battery and a lithium ion secondary battery were produced in the same manner as in Example 1, and measurements were conducted in the same manner as in Example 1. The results are shown in Table 1.

[Example 9]
Graphite powder of Example 9 is prepared in the same manner as Example 6, except that coke powder and tar pitch are mixed, stirred and pulverized to obtain pulverized powder, and then silicon carbide and spherical natural graphite are mixed with the pulverized powder. Obtained.
A negative electrode for a lithium ion secondary battery and a lithium ion secondary battery were produced in the same manner as in Example 1, and measurements were conducted in the same manner as in Example 1. The results are shown in Table 1.

[Example 10]
Graphite powder of Example 10 in the same manner as Example 2 except that the amounts of coke powder, tar pitch, silicon carbide and spherical natural graphite were changed to 41 parts by mass, 16 parts by mass, 16 parts by mass and 27 parts by mass, respectively. I got
A negative electrode for a lithium ion secondary battery and a lithium ion secondary battery were produced in the same manner as in Example 1, and measurements were conducted in the same manner as in Example 1. The results are shown in Table 1.

[Example 11]
A graphite powder of Example 11 is prepared in the same manner as Example 10 except that coke powder, tar pitch and silicon carbide are mixed, stirred and pulverized to obtain pulverized powder, and then spherical natural graphite is mixed with the pulverized powder. Obtained.
A negative electrode for a lithium ion secondary battery and a lithium ion secondary battery were produced in the same manner as in Example 1, and measurements were conducted in the same manner as in Example 1. The results are shown in Table 1.

[Example 12]
Graphite powder of Example 12 was prepared in the same manner as in Example 10 except that coke powder, tar pitch and spherical natural graphite were mixed, stirred and pulverized to obtain pulverized powder, and then silicon carbide was mixed with the pulverized powder. Obtained.
A negative electrode for a lithium ion secondary battery and a lithium ion secondary battery were produced in the same manner as in Example 1, and measurements were conducted in the same manner as in Example 1. The results are shown in Table 1.

[Example 13]
A graphite powder of Example 13 is prepared in the same manner as in Example 10 except that after mixing coke powder and tar pitch with stirring and pulverizing to obtain pulverized powder, silicon carbide and spherical natural graphite are mixed with the pulverized powder. Obtained.
A negative electrode for a lithium ion secondary battery and a lithium ion secondary battery were produced in the same manner as in Example 1, and measurements were conducted in the same manner as in Example 1. The results are shown in Table 1.

Example 14
Graphite powder of Example 14 in the same manner as in Example 2 except that the amounts of coke powder, tar pitch, silicon carbide and spherical natural graphite were changed to 29 parts by mass, 11 parts by mass, 5 parts by mass and 55 parts by mass, respectively. I got
A negative electrode for a lithium ion secondary battery and a lithium ion secondary battery were produced in the same manner as in Example 1, and measurements were conducted in the same manner as in Example 1. The results are shown in Table 1.

[Example 15]
The graphite powder of Example 15 is obtained in the same manner as in Example 14, except that coke powder, tar pitch and silicon carbide are mixed, stirred and pulverized to obtain pulverized powder, and then spherical natural graphite is mixed with the pulverized powder. Obtained.
A negative electrode for a lithium ion secondary battery and a lithium ion secondary battery were produced in the same manner as in Example 1, and measurements were conducted in the same manner as in Example 1. The results are shown in Table 1.

[Example 16]
A graphite powder of Example 16 is prepared in the same manner as in Example 14 except that coke powder, tar pitch and spherical natural graphite are mixed, stirred and pulverized to obtain pulverized powder, and then silicon carbide is mixed with the pulverized powder. Obtained.
A negative electrode for a lithium ion secondary battery and a lithium ion secondary battery were produced in the same manner as in Example 1, and measurements were conducted in the same manner as in Example 1. The results are shown in Table 1.

[Example 17]
The graphite powder of Example 17 is prepared in the same manner as in Example 14 except that after mixing coke powder and tar pitch with stirring and pulverizing to obtain pulverized powder, silicon carbide and spherical natural graphite are mixed with the pulverized powder. Obtained.
A negative electrode for a lithium ion secondary battery and a lithium ion secondary battery were produced in the same manner as in Example 1, and measurements were conducted in the same manner as in Example 1. The results are shown in Table 1.

[Example 18]
A graphite powder of Example 18 was obtained in the same manner as in Example 9, except that the same amount of mosaic coke having a lower degree of crystallinity than coke powder was used instead of the coke powder used in Example 9.
A negative electrode for a lithium ion secondary battery and a lithium ion secondary battery were produced in the same manner as in Example 1, and measurements were conducted in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 1
C. 100 parts by mass of coke powder, 40 parts by mass of tar pitch and 25 parts by mass of silicon carbide are heated and mixed at 250.degree. C., the resulting mixture is crushed, and then pressed into pellets and pressed in nitrogen at 900.degree. And fired at 3000.degree. C. using a graphitizing furnace. The obtained graphitized material was crushed using a hammer mill and sieved to obtain a graphite powder having an average particle diameter of 21 μm.

[Example 19]
A graphite powder of Example 19 is obtained in the same manner as in Example 9 except that spherical artificial graphite having an average particle diameter of 22 μm (circularity of 0.78) is used instead of spherical natural graphite used in Example 9 in the same amount. The
A negative electrode for a lithium ion secondary battery and a lithium ion secondary battery were produced in the same manner as in Example 1, and measurements were conducted in the same manner as in Example 1. The results are shown in Table 1.

[Example 20]
A graphite powder of Example 20 is obtained in the same manner as in Example 9 except that the same amount of spherical natural graphite having an average particle diameter of 23 μm (circularity of 0.95) is used instead of spherical natural graphite used in Example 9. The
A negative electrode for a lithium ion secondary battery and a lithium ion secondary battery were produced in the same manner as in Example 1, and measurements were conducted in the same manner as in Example 1. The results are shown in Table 1.

[Example 21]
A graphite powder of Example 21 is obtained in the same manner as in Example 9 except that the same amount of spherical natural graphite (circularity 0.90) having an average particle diameter of 10 μm is used instead of spherical natural graphite used in Example 9. The
A negative electrode for a lithium ion secondary battery and a lithium ion secondary battery were produced in the same manner as in Example 1, and measurements were conducted in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 2
A graphite powder of Comparative Example 2 was obtained in the same manner as in Example 9 except that the same amount of scaly natural graphite having an average particle diameter of 25 μm was used instead of the spherical natural graphite described in Example 9.
A negative electrode for a lithium ion secondary battery and a lithium ion secondary battery were produced in the same manner as in Example 1, and measurements were conducted in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 3
A graphite powder of Comparative Example 3 was obtained in the same manner as in Example 9 except that the same amount of scaly natural graphite adjusted to 20 μm with a sieve was used instead of the spherical natural graphite described in Example 9.
A negative electrode for a lithium ion secondary battery and a lithium ion secondary battery were produced in the same manner as in Example 1, and measurements were conducted in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 4
Only spherical natural graphite used in Example 1 was filled in a graphite crucible and fired at 2800 ° C. in a nitrogen atmosphere to obtain a graphite powder of Comparative Example 4.
A negative electrode for a lithium ion secondary battery and a lithium ion secondary battery were produced in the same manner as in Example 1, and measurements were conducted in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 5
A graphite powder of Comparative Example 5 was obtained in the same manner as in Example 1 except that coke powder was not used in Example 1.
A negative electrode for a lithium ion secondary battery and a lithium ion secondary battery were produced in the same manner as in Example 1, and measurements were conducted in the same manner as in Example 1. The results are shown in Table 1.

The graphite powders of Examples 1 to 21 contained composite particles including a plurality of flat graphite particles and spherical graphite particles, all of which were assembled or bonded so that the orientation planes were not parallel to each other.
Moreover, as shown in Table 1, the negative electrode material for lithium ion secondary batteries produced in the example was superior to the negative electrode material for lithium ion secondary batteries produced in the comparative example in rapid discharge retention rate (load characteristics) .

  The disclosure of Japanese Patent Application No. 2014-062431 is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards described herein are as specific and distinct as when individual documents, patent applications, and technical standards are incorporated by reference. Hereby incorporated by reference.

Claims (10)

It includes composite particles including a plurality of flat graphite particles which are aggregated or bonded so that the orientation planes are nonparallel and a spherical graphite particle, and the R value of Raman measurement is 0.03 or more and 0.10 or less , and the pore volume of pores having a pore diameter obtained by the mercury porosimetry at 8μm below the range of 0.1μm is Ri der less 0.2 mL / g or more 1.0 mL / g, an average particle diameter of 10μm~30μm The negative electrode material for lithium ion secondary batteries. The negative electrode material for a lithium ion secondary battery according to claim 1, wherein the specific surface area measured by BET method is 1.5 m ² / g or more and 6.0 m ² / g or less. Saturated tapping density of 0.8 g / cm ³ or more 1.2 g / cm ³ or less is claim 1 or negative electrode material for a lithium ion secondary battery according to claim 2.   The intensity ratio (P2 / P1) of the diffraction peak (P1) of the (101) plane of the hexagonal structure to the diffraction peak (P2) of the (101) plane of the rhombohedral structure in the X-ray diffraction pattern by CuKα ray is 0 It is .35 or less, The negative electrode material for lithium ion secondary batteries of any one of Claims 1-3.   The negative electrode material for a lithium ion secondary battery according to any one of claims 1 to 4, wherein the degree of circularity of the spherical graphite particles is 0.8 or more. 2. A method comprising: (a) obtaining a mixture comprising graphitizable aggregate or graphite, a graphitizable binder, a graphitization catalyst and spherical graphite particles, and (b) calcining the mixture. The manufacturing method of the negative electrode material for lithium ion secondary batteries of any one of-Claim 5.   7. The method according to claim 6, further comprising, between the step (a) and the step (b), at least one selected from the group consisting of (c) shaping the mixture and (d) heat treating the mixture. The manufacturing method of the negative electrode material for lithium ion secondary batteries as described.   The negative electrode material for a lithium ion secondary battery according to any one of claims 1 to 5 or the method for producing a negative electrode material for a lithium ion secondary battery according to claim 6 or 7 A negative electrode material slurry for a lithium ion secondary battery, comprising a negative electrode material for a lithium ion secondary battery, an organic binder, and a solvent.   A lithium ion secondary battery comprising a current collector, and a negative electrode material layer containing the negative electrode material for a lithium ion secondary battery according to any one of claims 1 to 5 formed on the current collector. Negative electrode.   The lithium ion secondary battery which has a positive electrode, electrolyte, and the negative electrode for lithium ion secondary batteries of Claim 9.